In welding, prior to cutting with a welding torch, soapstone is generally used as a marking means to draw an appropriate thin line on the metal to be cut by an acetylene torch, for example. The soapstone is similarly used in other metal work for marking to indicate breaking and cutting lines, for example.
In order to mark the metal with a thin line, the soapstone, which normally comes in a rectangular prism form, is typically sharpened at one end to have a thin line edge. In the prior art this has been primarily done by rubbing one end, first one side and then the other, on an abrasive material until the thin line edge is formed. Such prior art sharpening is relatively slow and tedious. It is also difficult to obtain the desired thin line edge in such sharpening.